A TiO₂-Au-polymer hybrid system for the photoelectrochemical immunoassay of SirT1

Human sirtuin1 (SirT1), which is a member of the sirtuin family, plays an important role in a wide range of cellular processes. Here we demonstrate a new strategy for the photoelectrochemical assay of SirT1 in different cell lines based on a semiconductor-polymer hybrid system consisting of Au-polymer and TiO₂-Au nanocomposites. Au-polymer (GC-HBAP) hybrids were synthesized from crosslinked hyperbranched azo-polymer and gold colloids and then used as an immobilization platform for SirT1 antibody. Gold-doped TiO₂ (TiO₂-Au) nanocomposites were prepared as the photoelectrochemical labels for signal readout in the sandwiched immunoassay. The integration of GC-HBAP with TiO₂-Au facilitated the electron transfer and the photoelectrocatalytic reaction, resulting in good analytical performance with high sensitivity, selectivity and rapid response for the analysis of SirT1 levels in different cell lines. This proposed semiconductor-polymer system might open a new perspective for the development of a highly sensitive photoelectrochemical immunosensor, and have potentially promising applications in assays of other proteins.